Chapter 9 opinion of second language

In chapter 9, we learned that it is proven that when learning a second language, it is definitly better to start learning it as early as possible. This makes me wonder why we don't start learning Spanish in school until our high school years. Last year, we hosted an exchanged student from Denmark, and she started learning English and German in fourth grade and barely had an accent and had almost perfect grammar when she came. Also, having already learned 3 languages, it made it much easier for her to pick up Spanish in class and learn Japanese on her own while here. It just seems so much more convenient and I wish that I had done so as well. I wonder why we don't learn languages as early. She had so many more opportunities, having learned so many languages, to travel all over the world. If America is the land of opportunity, shouldn't we have the same chance?